1. Field of the Invention
The invention relates to a circuit for providing a selection signal for a control value of a control variable which, in a steady state, oscillates, about a reference variable, between a first control value and a second control value with a first period duration.
2. Description of the Related Art
The technical field of the invention relates to the control of one or more components in an electronic circuit or integrated circuit. In this case, a control variable, in particular a digital control variable, for the electronic component or components is controlled to a predeterminable reference variable. The problem of the control system entering, the steady state after a particular stabilization time and of the variable to be controlled or the control variable, for example a voltage for supplying voltage to the electronic component, oscillating back and forth between two control values is known from a multiplicity of such control-engineering circuits. In this case, there generally exists the problem of only one of the two values between which the control variable oscillates having a minimum control difference from the reference variable.
In order to explain the present problems, FIGS. 1a and 1b show a schematic diagram for illustrating the oscillation of a control variable in a steady state. In this case, FIG. 1a illustrates the control variable RG which oscillates about the reference variable RefG as a function of time t. FIG. 1b shows that the maximum amplitude of the oscillation of the control variable RG is in the form of a first control value RW1 and that the minimum amplitude of the control variable RG is in the form of a second control value RW2. The control system thus alternately decides on the first control value RW1 or the second control value RW2. In this case, there exists the problem of the control system not deciding on that control value which has the smallest control difference from the reference variable RefG (the control value RW2 in this case) and instead an unnecessarily large control difference from the reference variable RefG being generated for the control variable RG on account of the first control value RW1 being alternately decided on in the steady state.